A technique of performing a fail-safe at the time of failure in a rotation speed sensor of a secondary pulley of a continuously variable transmission is disclosed in JP5-46465B. In this technique, the continuously variable transmission is shifted by a single pressure regulation method of fixing control pressure of the secondary pulley to line pressure. In this technique, at the time of failure in the rotation speed sensor of the secondary pulley, the line pressure transmitted straightaway as the control pressure of the secondary pulley is fixed to the maximum value. In this technique, control pressure of a primary pulley generated from the line pressure is made to have the minimum value and a speed ratio is fixed to the maximum speed ratio, that is, the lowest speed ratio. Thereby, belt slippage is prevented in this technique.